GO:0032798 Swi5-Sfr1 complex: Components, Assembly and Research Methods
Research-grade guide for scientists and biopharma professionals
Key Takeaways
• GO:0032798 defines the Swi5-Sfr1 complex, a conserved DNA recombinase mediator complex containing two Swi5 monomers and one Sfr1 monomer in Schizosaccharomyces, or orthologs such as Sae3p and Mei5p in Saccharomyces.
• The complex stimulates Rad51- and Dmc1-mediated DNA strand exchange, the central step of homologous recombination.
• It stabilizes the Rad51 presynaptic filament and enhances ADP release, promoting the active ATP-bound state.
• The complex proceeds through two distinct three-stranded intermediates during strand exchange, with different mechanisms for Dmc1 and Rad51.
• Mammalian orthologs are involved in DNA strand break repair and homologous recombination.
• Research tools include knockout, point mutation, knock-in, overexpression, and CRISPR library screening to dissect its function.
Description
The Swi5-Sfr1 complex (GO:0032798) is a conserved DNA recombinase mediator complex that contains two Swi5 monomers and one Sfr1 monomer in Schizosaccharomyces, or orthologs thereof (e.g. Sae3p and Mei5p in Saccharomyces). It is a cellular component that plays a critical role in homologous recombination, a process essential for genome maintenance and genetic diversity. The complex was initially identified in fission yeast as a factor that stimulates Rad51- and Dmc1-mediated DNA strand exchange in vitro. Since then, structural and biochemical studies have revealed that the Swi5-Sfr1 complex forms an elongated dogleg-shaped structure and interacts with Rad51 to stabilize the presynaptic filament. These findings have positioned the complex as a key mediator of recombinase function across species, from yeast to mammals. Researchers study GO:0032798 to understand the molecular mechanisms of homologous recombination, DNA repair, and their implications in cancer and genetic diseases. The complex is also a target for CRISPR-based functional genomics, as its components can be knocked out, mutated, or overexpressed to dissect their roles in DNA repair pathways.
Swi5-Sfr1 complex At A Glance
| GO ID | GO:0032798 |
|---|---|
| GO term | Swi5-Sfr1 complex |
| Ontology | Cellular component |
| Synonym | Sae3-Mei5 complex, Swi5 complex |
| Major function | Stimulates Rad51- and Dmc1-mediated DNA strand exchange; stabilizes presynaptic filament; enhances ADP release |
| Subunit composition | Two Swi5 monomers and one Sfr1 monomer in Schizosaccharomyces; orthologs Sae3p and Mei5p in Saccharomyces |
| Structural feature | Extremely elongated dogleg-shaped structure |
| Conservation | Conserved from yeast to mammals |
| Related process | Homologous recombination, DNA strand break repair |
What Is GO:0032798?
The Swi5-Sfr1 complex is a conserved DNA recombinase mediator complex that contains two Swi5 monomers and one Sfr1 monomer in Schizosaccharomyces, or orthologs thereof (e.g. Sae3p and Mei5p in Saccharomyces). It is classified under the cellular component ontology (GO:0032798).
Why Is Swi5-Sfr1 complex Important in Cell Biology?
The Swi5-Sfr1 complex is important because it is a critical mediator of homologous recombination, a high-fidelity DNA repair pathway that maintains genome stability. By stimulating Rad51- and Dmc1-mediated DNA strand exchange, the complex ensures efficient repair of DNA double-strand breaks and proper chromosome segregation during meiosis. Dysregulation of homologous recombination is associated with cancer predisposition and chemotherapy resistance, making the complex a potential target for therapeutic intervention. Moreover, understanding its mechanism provides insights into fundamental DNA repair processes and informs the development of CRISPR-based tools for genome editing.
• Stimulates Rad51- and Dmc1-mediated DNA strand exchange, the central step of homologous recombination.
• Stabilizes the Rad51 presynaptic filament, preventing dissociation and promoting strand invasion.
• Enhances ADP release from Rad51, facilitating the transition to the active ATP-bound state.
• Involved in DNA strand break repair through homologous recombination in mammals.
• Conserved from yeast to humans, making it a model for studying recombinase mediators.
• Potential role in cancer biology, as homologous recombination defects are linked to tumorigenesis.
• Target for CRISPR knockout, point mutation, and overexpression studies to dissect DNA repair pathways.
• Structural studies reveal an elongated dogleg shape, providing insights into protein-protein interactions.
• Regulates both mitotic and meiotic recombination, impacting genetic diversity and genome stability.
• Can be studied using biochemical assays, structural biology, and functional genomics.
What Happens During Swi5-Sfr1 complex?
Stimulation of Rad51-mediated DNA strand exchange
In simple terms: The Swi5-Sfr1 complex helps Rad51 do its job of swapping DNA strands during repair.
The Swi5-Sfr1 complex directly stimulates Rad51-mediated DNA strand exchange, a key step in homologous recombination. In vitro studies using purified proteins from fission yeast showed that the complex enhances the strand exchange activity of Rhp51/Rad51. More recent work revealed that the stimulation proceeds through two distinct three-stranded intermediates, with different mechanisms for Dmc1- and Rad51-driven reactions. The complex achieves this by promoting the formation and stabilization of the Rad51 presynaptic filament.
Stabilization of the Rad51 presynaptic filament
In simple terms: The complex acts like a clamp that keeps the Rad51 filament from falling apart.
The mouse Swi5-Sfr1 heterodimeric complex stabilizes the Rad51 presynaptic filament, a nucleoprotein filament that forms on single-stranded DNA and is essential for strand invasion. This stabilization is critical because the filament is inherently dynamic and can dissociate, leading to failed recombination. The complex binds to Rad51 and prevents filament disassembly, thereby promoting efficient DNA strand exchange.
Enhancement of ADP release from Rad51
In simple terms: The complex helps Rad51 get rid of used-up energy molecules so it can bind fresh ones.
The Swi5-Sfr1 complex enhances the release of ADP from the Rad51 presynaptic filament, facilitating the exchange of ADP for ATP. This nucleotide exchange is essential for Rad51 to attain its active ATP-bound state, which is required for DNA strand exchange. By accelerating ADP release, the complex ensures that Rad51 remains in a catalytically active conformation.
Cooperative interactions with Rad51
In simple terms: The complex and Rad51 work together in a coordinated way to promote recombination.
Cooperative interactions between the Swi5-Sfr1 complex and Rad51 facilitate the stimulation of Rad51 activity. This cooperativity likely involves multiple binding interfaces and allosteric regulation, allowing the complex to efficiently promote filament formation and strand exchange even at low concentrations. Such cooperative behavior is a hallmark of mediator complexes in homologous recombination.
Role in Dmc1-mediated recombination
In simple terms: The complex also assists Dmc1, a related protein that handles DNA swapping during meiosis.
The Swi5-Sfr1 complex stimulates Dmc1-mediated DNA strand exchange, which is essential for meiotic recombination. Dmc1 is a meiosis-specific recombinase that forms filaments on single-stranded DNA and catalyzes strand invasion. The complex enhances Dmc1 activity through mechanisms that may differ from those used for Rad51, as evidenced by the distinct three-stranded intermediates observed.
Key Genes Involved in GO:0032798 Swi5-Sfr1 complex
The following genes and proteins are key components or interactors of the Swi5-Sfr1 complex, based on published literature.
| Gene | Major Role | Research Relevance |
|---|---|---|
| Swi5 (Schizosaccharomyces pombe) | Core subunit of the Swi5-Sfr1 complex; two monomers per complex | Essential for complex formation and stimulation of Rad51/Dmc1 |
| Sfr1 (Schizosaccharomyces pombe) | Core subunit of the Swi5-Sfr1 complex; one monomer per complex | Required for complex stability and mediator function |
| Sae3p (Saccharomyces cerevisiae) | Ortholog of Swi5 | Meiotic recombination mediator |
| Mei5p (Saccharomyces cerevisiae) | Ortholog of Sfr1 | Meiotic recombination mediator |
| Rad51 | Eukaryotic recombinase; forms presynaptic filament | Target of Swi5-Sfr1 stimulation |
| Dmc1 | Meiosis-specific recombinase | Stimulated by Swi5-Sfr1 during meiosis |
| Rhp51 (S. pombe) | Fission yeast Rad51 ortholog | Stimulated by Swi5-Sfr1 |
| RAD51 (human) | Human recombinase | Mammalian Swi5-Sfr1 orthologs may regulate RAD51 |
| Swi5 (mouse) | Mammalian ortholog of Swi5 | Forms heterodimer with Sfr1; stabilizes RAD51 filament |
| Sfr1 (mouse) | Mammalian ortholog of Sfr1 | Forms heterodimer with Swi5; stabilizes RAD51 filament |
| BRCA2 | Homologous recombination mediator | Functional interplay with Swi5-Sfr1 pathway |
| RAD51AP1 | Rad51 accessory factor | Potential cooperative interactions |
| RAD54 | Chromatin remodeler in HR | May cooperate with Swi5-Sfr1 |
| MND1 | Meiotic recombination factor | Interacts with Dmc1 |
| HOP2 | Meiotic recombination factor | Interacts with Dmc1 |
| RPA | Single-stranded DNA-binding protein | Plays a role in presynaptic filament formation |
| ATP | Energy molecule | Required for Rad51 active state; ADP release enhanced by Swi5-Sfr1 |
| ADP | Nucleotide | Release from Rad51 enhanced by Swi5-Sfr1 |
How Is Swi5-Sfr1 complex Regulated?
The Swi5-Sfr1 complex is regulated at multiple levels. Its activity is dependent on cooperative interactions with Rad51, which facilitate stimulation of Rad51 by the complex. The complex also enhances ADP release from the Rad51 presynaptic filament, which is a key regulatory step in the ATPase cycle of Rad51. Post-translational modifications and cell cycle-dependent expression may further control its function, although specific regulatory mechanisms remain to be fully elucidated. In mammals, the complex is involved in DNA strand break repair through homologous recombination, suggesting that its activity is integrated with the DNA damage response.
Swi5-Sfr1 complex and Human Disease
| Gene | Disease / Biology | Potential Experimental Model |
|---|---|---|
| Swi5/Sfr1 (mammalian) | Homologous recombination deficiency; cancer predisposition | Knockout mouse models; cancer cell lines |
| Swi5/Sfr1 (yeast) | Meiotic defects; infertility | S. pombe or S. cerevisiae knockout strains |
| RAD51 | Cancer; Fanconi anemia-like phenotypes | CRISPR knockout in human cell lines |
| Dmc1 | Meiotic arrest; infertility | Mouse knockout models |
| BRCA2 | Breast/ovarian cancer | Patient-derived organoids; CRISPR knock-in |
Cancer and homologous recombination deficiency
Defects in homologous recombination, including components of the Swi5-Sfr1 complex, can lead to genomic instability and cancer predisposition. The mammalian Swi5-Sfr1 complex plays a role in DNA strand break repair through homologous recombination. Loss of function of such mediator complexes may contribute to the development of cancers with HR deficiency, such as breast and ovarian cancers. Understanding the complex's function could inform therapeutic strategies targeting HR-deficient tumors.
Meiotic defects and infertility
The Swi5-Sfr1 complex is essential for meiotic recombination, as it stimulates Dmc1-mediated DNA strand exchange. Disruption of the complex could lead to meiotic arrest, improper chromosome segregation, and infertility. Studies in model organisms have shown that mutations in Swi5 or Sfr1 orthologs result in meiotic defects, highlighting their importance in germ cell development.
Neurodegeneration and genome instability
Impaired DNA repair pathways, including homologous recombination, are associated with neurodegenerative diseases characterized by genome instability. While direct links between the Swi5-Sfr1 complex and neurodegeneration are not yet established, its role in DNA strand break repair suggests that its dysfunction could contribute to neuronal cell death under conditions of oxidative stress.
From Swi5-Sfr1 complex-Related Genes to Experimental Models
| Research Question | Suitable Model |
|---|---|
| Does Swi5-Sfr1 complex stimulate Rad51-mediated strand exchange? | In vitro biochemical assay with purified proteins |
| What is the structural basis of Swi5-Sfr1 function? | X-ray crystallography or cryo-EM |
| What is the role of Swi5-Sfr1 in DNA repair in vivo? | CRISPR knockout in human cell lines |
| How does Swi5-Sfr1 affect meiotic recombination? | Yeast genetics; mouse knockout models |
| Does Swi5-Sfr1 enhance ADP release from Rad51? | Fluorescence-based nucleotide exchange assays |
| Can Swi5-Sfr1 be targeted for cancer therapy? | Patient-derived xenografts; CRISPR screening |
How to Study the Swi5-Sfr1 complex Process
| Method | What It Measures | Typical Application |
|---|---|---|
| DNA strand exchange assay | Recombinase activity | Testing Swi5-Sfr1 stimulation of Rad51/Dmc1 |
| X-ray crystallography | Three-dimensional structure | Determining Swi5-Sfr1 architecture |
| Cryo-EM | High-resolution structure | Visualizing complex with Rad51 filament |
| CRISPR knockout | Gene function in cells | Assessing HR efficiency and drug sensitivity |
| Fluorescence nucleotide exchange assay | ADP release rate | Measuring Swi5-Sfr1 enhancement of ADP release |
| Single-molecule FRET | Real-time dynamics | Observing filament stabilization |
| Yeast genetics | Meiotic recombination | Testing ortholog functions |
| Proteomics | Protein interactions | Identifying novel partners of Swi5-Sfr1 |
Biochemical reconstitution and strand exchange assays
Biochemical reconstitution using purified Swi5-Sfr1 complex and Rad51 or Dmc1 allows direct measurement of DNA strand exchange activity. These assays typically use radiolabeled or fluorescently labeled DNA substrates and can reveal the mechanism of stimulation, including the formation of three-stranded intermediates.
Structural biology (crystallography and cryo-EM)
Structural studies, such as X-ray crystallography and cryo-electron microscopy, have revealed that the Swi5-Sfr1 complex forms an extremely elongated dogleg-shaped structure. Crystallization of the complex has been achieved, and high-resolution structures can provide insights into interaction interfaces with Rad51 and the mechanism of filament stabilization.
CRISPR-based functional genomics
CRISPR knockout, point mutation, and knock-in models enable functional dissection of Swi5-Sfr1 complex components in cells. For example, knocking out Swi5 or Sfr1 in human cell lines can reveal their roles in DNA repair and sensitivity to DNA-damaging agents. Overexpression studies can test gain-of-function phenotypes.
Single-molecule and fluorescence imaging
Single-molecule fluorescence resonance energy transfer (smFRET) and total internal reflection fluorescence (TIRF) microscopy can visualize the dynamics of Rad51 filament formation and stabilization by the Swi5-Sfr1 complex in real time. These techniques provide quantitative insights into cooperative interactions and nucleotide exchange.
How CRISPR Can Be Used to Study GO:0032798 Swi5-Sfr1 complex
Knockout
CRISPR knockout of Swi5 or Sfr1 orthologs in human cell lines can abolish the Swi5-Sfr1 complex, leading to defective homologous recombination and increased sensitivity to DNA-damaging agents. Such models are valuable for studying the complex's role in DNA repair and cancer.
Point Mutation
Point mutations can be introduced into Swi5 or Sfr1 to disrupt specific interaction interfaces or catalytic residues. For example, mutations that impair Rad51 binding or ADP release can be generated to dissect the molecular mechanism of the complex.
Knock-in
Knock-in of tagged versions of Swi5 or Sfr1 (e.g., GFP or FLAG) allows for endogenous expression and localization studies. This approach can reveal the spatiotemporal dynamics of the complex during the cell cycle and in response to DNA damage.
Overexpression
Overexpression of Swi5-Sfr1 complex components can be used to test gain-of-function phenotypes, such as enhanced homologous recombination or resistance to DNA-damaging agents. Overexpression models can also facilitate biochemical purification of the complex for in vitro studies.
How EDITGENE Supports Swi5-Sfr1 complex Research
Researchers studying Swi5-Sfr1 complex-related genes often need to determine whether a candidate gene is causally involved in homologous recombination, DNA repair, or disease. EDITGENE provides a comprehensive suite of CRISPR-based services to enable such investigations, from knockout and point mutation to knock-in and overexpression, as well as library screening and bioinformatics support.
Contact EDITGENE today to design your custom CRISPR model for Swi5-Sfr1 complex research.
Frequently Asked Questions About Swi5-Sfr1 complex
What is the Swi5-Sfr1 complex?
The Swi5-Sfr1 complex is a conserved DNA recombinase mediator complex that contains two Swi5 monomers and one Sfr1 monomer in Schizosaccharomyces, or orthologs such as Sae3p and Mei5p in Saccharomyces. It stimulates Rad51- and Dmc1-mediated DNA strand exchange.
What genes are involved in the Swi5-Sfr1 complex?
The core genes are Swi5 and Sfr1 in fission yeast, with orthologs Sae3p and Mei5p in budding yeast. In mammals, the orthologs are also called Swi5 and Sfr1.
What is the function of GO:0032798?
GO:0032798 is a cellular component ontology term that defines the Swi5-Sfr1 complex. Its function is to mediate DNA strand exchange by stimulating Rad51 and Dmc1 recombinases.
How does the Swi5-Sfr1 complex stimulate Rad51?
It stabilizes the Rad51 presynaptic filament and enhances ADP release, promoting the active ATP-bound state of Rad51.
What is the structure of the Swi5-Sfr1 complex?
The complex forms an extremely elongated dogleg-shaped structure, as revealed by structural studies.
Is the Swi5-Sfr1 complex conserved in humans?
Yes, orthologs of Swi5 and Sfr1 exist in mammals, and the complex plays a role in DNA strand break repair through homologous recombination.
What diseases are associated with Swi5-Sfr1 complex dysfunction?
Dysfunction may lead to homologous recombination deficiency, cancer predisposition, and meiotic defects.
How can I study the Swi5-Sfr1 complex using CRISPR?
CRISPR knockout, point mutation, knock-in, and overexpression models can be used to dissect its function in DNA repair and recombination.
What are the synonyms for Swi5-Sfr1 complex?
Synonyms include Sae3-Mei5 complex and Swi5 complex.
What methods are used to study the Swi5-Sfr1 complex?
Common methods include DNA strand exchange assays, X-ray crystallography, cryo-EM, CRISPR screening, and single-molecule imaging.
Conclusion
The Swi5-Sfr1 complex (GO:0032798) is a conserved mediator of homologous recombination that stimulates Rad51- and Dmc1-mediated DNA strand exchange. Its structural and functional properties have been elucidated through biochemical, structural, and genetic studies. Dysregulation of the complex is linked to cancer and meiotic defects, making it a target for therapeutic intervention and functional genomics. EDITGENE provides comprehensive CRISPR services to study the Swi5-Sfr1 complex and its role in DNA repair.
References
- 1. Ito K et al.. 2024. The Swi5-Sfr1 complex regulates Dmc1- and Rad51-driven DNA strand exchange proceeding through two distinct three-stranded intermediates by different mechanisms.. Nucleic Acids Res 52(20):12517-12533 PMID: 39340300
- 2. Argunhan B et al.. 2020. Cooperative interactions facilitate stimulation of Rad51 by the Swi5-Sfr1 auxiliary factor complex.. Elife 9 PMID: 32204793
- 3. Akamatsu Y et al.. 2010. Role for the mammalian Swi5-Sfr1 complex in DNA strand break repair through homologous recombination.. PLoS Genet 6(10):e1001160 PMID: 20976249
- 4. Tsai SP et al.. 2012. Rad51 presynaptic filament stabilization function of the mouse Swi5-Sfr1 heterodimeric complex.. Nucleic Acids Res 40(14):6558-69 PMID: 22492707
- 5. Kuwabara N et al.. 2010. Expression, purification and crystallization of Swi5 and the Swi5-Sfr1 complex from fission yeast.. Acta Crystallogr Sect F Struct Biol Cryst Commun 66(Pt 9):1124-6 PMID: 20823543
- 6. Kokabu Y et al.. 2011. Fission yeast Swi5-Sfr1 protein complex, an activator of Rad51 recombinase, forms an extremely elongated dogleg-shaped structure.. J Biol Chem 286(50):43569-76 PMID: 22033972
- 7. Haruta N et al.. 2006. The Swi5-Sfr1 complex stimulates Rhp51/Rad51- and Dmc1-mediated DNA strand exchange in vitro.. Nat Struct Mol Biol 13(9):823-30 PMID: 16921379
- 8. Su GC et al.. 2014. Enhancement of ADP release from the RAD51 presynaptic filament by the SWI5-SFR1 complex.. Nucleic Acids Res 42(1):349-58 PMID: 24078249
